En route to inherently chiral tetraoxacalix[2]arene[2]triazines

This paper describes our attempts to synthesize inherently chiral heteroatom-bridged calixaromatics. Based on a stepwise fragment-coupling approach using a chiral 3,5-dihydroxybenzamide or benzoate, 2,4-dihydroxyacetophenone, and cyanuric chloride as reactants, chiral tetraoxacalix[2]arene[2]triazine derivatives 16 and 17 were synthesized in good yields. Subsequent macrocyclic condensation with a diamine 6 furnished efficiently the pairs of diastereomers of inherently chiral tetraoxacalix[2]arene[2]triazine azacrowns 18 and 19.